Illinois Audubon Society—A Dip Net and Creatures Wet Quiz

A Dip Net and Creatures Wet by Patty Gillespie

Here is a perfect quiz to follow on the heels of our shorebird quiz! Let’s learn about some of those critters shorebirds are searching for in the mudflats and shallow waters.

Along the shore of a lake or at the edge of a river or beside a wetland, I extend my reach, dip my net down through the shallows, skim it along the bottom, and tug it back. As I lift the net, water drips through. Aquatic species assemble at the bottom of the net. Some wiggle and squirm; some shimmer and sparkle reflecting sunlight; some jump and flip.

Certain aquatic organisms can serve as indicator species during biological monitoring. A number of macroinvertebrates are “intolerant”; such species are not capable of surviving within an aquatic environment tainted by pollutants nor within water bodies depleted of oxygen. Others, such as rat-tailed maggots and mosquito larvae, can thrive in yucky water. If the “intolerant” or highly sensitive species are discovered within the whole mix of organisms in the dip net, then the water is considered “good quality,” suggesting that a body of water can support a complex and diverse aquatic community. Learn more about an aquatic habitat monitoring project, Illinois RiverWatch, in the summer 2020 edition of Illinois Audubon.

Choose which of the two pictured organisms exhibits the characteristic(s) described in each statement.

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1. The gills of this insect nymph are located inside a special chamber (rectum) within its abdomen. The nymph breathes by drawing water in and out of its hind end.

Correct, (B) is a dragonfly nymph. Explanation: The gills of a dragonfly nymph (B) are located within the body cavity while the gills of a damselfly (A) are external, resembling tails at the end of its abdomen.

(A) is a damselfly nymph. The correct answer is (B), dragonfly nymph. Explanation: The gills of a dragonfly nymph (B) are located within the body cavity while the gills of a damselfly (A) are external, resembling tails at the end of its abdomen.

2. This decapod is omnivorous, feeding upon vegetation or preying upon snails and other macroinvertebrates and small fish. It has two defense mechanisms. It has large claws on its first pair of legs for pinching. Also, it has expendable legs. When this creature is attacked, muscles in the walking legs may contract at creases and may break off. The missing legs regenerate with molt.

Correct, (B) is a crayfish or crawdad! Explanation: Although the ghost shrimp (A) and crayfish (B) are both decapods and crustaceans, the crayfish‘s claws are able to crush the shells of snails upon which it preys, as well as to pinch whomever the crayfish considers an attacker.

(A) is a ghost shrimp. The correct answer is (B) crayfish or crawdad. Explanation: Although the ghost shrimp (A) and crayfish (B) are both decapods and crustaceans, the crayfish‘s claws are able to crush the shells of snails upon which it preys, as well as to pinch whomever the crayfish considers an attacker.

3. This aquatic insect has long oar-like hind legs used for swimming and feeds by inserting its beak into its prey and sucking out its bodily fluids.

Correct, (A) is a backswimmer! Explanation: A backswimmer (A) is a true bug (Hemiptera) with a beak or mouthparts used for jabbing or puncturing and sucking. A whirligig beetle (B) is a beetle (Coleoptera) with mandibulate or chewing mouth parts.

(B) is a whirligig beetle. The correct answer is (A), backswimmer. Explanation: A backswimmer (A) is a true bug (Hemiptera) with a beak or mouthparts used for jabbing or puncturing and sucking. A whirligig beetle (B) is a beetle (Coleoptera) with mandibulate or chewing mouth parts.

4. This insect undergoes an incomplete metamorphosis. This benthic macroinvertebrate is fairly sensitive to changes in the ecological integrity of a body of water and serves as one of the indicator organisms observed by participants in the Illinois RiverWatch monitoring project.

Correct, (B) damselfly nymph! Explanation: Both the damselfly nymph (B) and beetle larva (A) are bioindicators used in water quality assessment, but the damselfly undergoes an incomplete metamorphosis (egg, nymph, adult), while the beetle undergoes a complete metamorphosis (egg, larva, pupa, adult).

(A) is a beetle larva. The correct answer is (B), damselfly nymph. Explanation: Both the damselfly nymph (B) and beetle larva (A) are bioindicators used in water quality assessment, but the damselfly undergoes an incomplete metamorphosis (egg, nymph, adult), while the beetle undergoes a complete metamorphosis (egg, larva, pupa, adult).

5. This invertebrate must remain moist. To prevent desiccation, the organism produces a protective coat of mucus which also aids in travel as it moves by rhythmic waves of muscular contractions, leaving a slime trail behind.

Correct, (A) is a slug. Explanation: The slug (A) is a terrestrial gastropod, related to snails but without a shell. Find a slug and you may notice its slime trail. The leech (B) is an annelid, or worm, and is known for its blood-sucking abilities.

(B) is a leech. The correct answer is (A), slug. Explanation: The slug (A) is a terrestrial gastropod, related to snails but without a shell. Find a slug and you will notice a slime trail. The leech (B) is an annelid, or worm, and is known for its blood-sucking abilities.

6. This fish gives birth to live offspring instead of laying eggs and is generally seen in small creeks or along vegetation in ponds and lakes.

Correct! Explanation: (B) Western mosquito fish (Gambusia affinis), unlike most lake-dwelling fish, give birth to live offspring. Adult female (A) bluegill (Lepomis macrochirus) deposit eggs in spawning beds, basins which the fish create within the substrate in shallows at the edges of water bodies.

(B) is a bluegill (Lepomis macrochirus). The correct answer is (A), western mosquito fish. Explanation: (B) Western mosquito fish (Gambusia affinis), unlike most lake-dwelling fish, give birth to live offspring. Adult female (A) bluegill (Lepomis macrochirus) will deposit eggs in spawning beds, basins which the fish create within the substrate in shallows at the edges of water bodies.

7. This aquatic larva will change into an adult form that prefers a moist subterranean habitat in an upper humus-rich soil horizon (beneath rotting logs, within leaf litter, or under grassy detritus), except during breeding season when it returns to water.

Correct, (A) is a salamander larva! Explanation: Salamanders (A) are amphibians that generally require water for reproductive purposes (mating, egg-laying, and larval development).The common adult salamanders in Illinois (ie. smallmouth salamander, tiger salamander) live most of their lives in a subterranean habitat. Tadpole (B) is an immature stage of a frog, an amphibian. Common frog species (ie. chorus frog, spring peeper, and bullfrog) are terrestrial as adults but rarely venture beneath the soil surface as salamanders do. However, frogs may hibernate during winter in the mud at the bottom of a water body.

(B) is a frog larva or tadpole. The correct answer is (A) salamander larva. Explanation: Salamanders (A) are amphibians that generally require water for reproductive purposes (mating, egg-laying, and larval development).The common adult salamanders in Illinois (ie. smallmouth salamander, tiger salamander) live most of their lives in a subterranean habitat. Tadpole (B) is an immature stage of a frog, an amphibian. Common frog species (ie. chorus frog, spring peeper, and bullfrog) are terrestrial as adults but rarely venture beneath the soil surface as salamanders do. However, frogs may hibernate during winter in the mud at the bottom of a water body.

8. This grouping of organisms, found within a shallow pond in a forested area, has a firm gelatinous texture and filters food from water by use of lophophores crowned with tiny tentacles.

Correct, (A) is a bryozoan colony! Explanation: The freshwater bryozoan (A) is a filter-feeder. An amalgamation of frog eggs (B) must remain moist or wet for the period of embryotic development, but the eggs do not utilize the watery surroundings for food.

(B) is an amalgamation of frog eggs. The correct answer is (A), a bryozoan colony. Explanation: The freshwater bryozoan (A) is a filter-feeder. An amalgamation of frog eggs (B) must remain moist or wet for the period of embryotic development, but the eggs do not utilize the watery surroundings for food.

9. This snake is diurnal during spring and fall but becomes nocturnal in summer and hibernates during winter’s cold. The nonvenomous snake is sometimes called “water moccasin” perhaps due to its aquatic habits, foraging for fish and amphibians, basking along shorelines, loafing on branches overhanging water, and taking shelter under debris at water’s edge.

Correct, (A) is a northern banded water snake. Explanation: Northern banded water snake (A) (Nerodia sipedon) Is sometimes called “water moccasin, a name used to refer to snakes who prefer an aquatic habitat. The nonvenomous northern banded water snake is sometimes mistaken for a cottonmouth perhaps due to similarities in appearance and habits. The garter snake (B) (Thamnophis sirtalis) does frequent wet environments (ditches, ponds, ephemeral pools), but it will often travel and hunt prey away from water. It is seldom called a water moccasin.

(B) is a garter snake (Thamnophis sirtalis). The correct answer is (A), northern banded water snake. Explanation: Northern banded water snake (A) (Nerodia sipedon) Is sometimes called “water moccasin, a name used to refer to snakes who prefer an aquatic habitat. The nonvenomous northern banded water snake is sometimes mistaken for a cottonmouth perhaps due to similarities in appearance and habits. The garter snake (B) (Thamnophis sirtalis) does frequent wet environments (ditches, ponds, ephemeral pools), but it will often travel and hunt prey away from water. It is seldom called a water moccasin.

10. This frog’s voice is often heard in early spring during its breeding season. Its loud voice belies its small size of only 4 cm or 1 ½ inches snout-to-vent length at maturity.

Correct, (A) is a chorus frog! Explanation: Both the chorus frog (A) (Pseudacris spp.) and the leopard frog (B) (Rana spp.) make their presence known during spring mating season, but the chorus frog grows to only about an inch and a half. The leopard frog can reach the size of 9 cm or 3.5 inches.

(B) is a leopard frog. The correct answer is (A), chorus frog. Explanation: Both the chorus frog (A) (Pseudacris spp.) and the leopard frog (B) (Rana spp.) make their presence known during spring mating season, but the chorus frog grows to only about an inch and a half. The leopard frog can reach the size of 9 cm or 3.5 inches.